Why Are GitLab Shared Runners So Slow?

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GitLab Shared Runners: Convenience at a Cost

GitLab shared runners offer an easy and cost-effective way to execute CI/CD pipelines, particularly for small to mid-sized projects. However, many users encounter frustratingly slow performance, which can lead to missed deadlines and reduced productivity.

Why is this the case? Let’s dive into the key reasons behind the slowness of GitLab shared runners.


1. Limited Resources

GitLab shared runners operate on n1-standard-1 instances from Google Cloud Platform (GCP). These instances provide minimal system resources, such as:

  • 1 vCPU
  • 3.75 GB of memory

For pipelines involving compute-intensive tasks—such as large builds, complex test suites, or Docker image creation—these limited resources can quickly become a bottleneck. Additionally, if multiple jobs run on the same runner, resource contention further degrades performance.


2. Lack of Multithreading

GitLab shared runners are limited to a single core, making parallel execution impossible. Tasks that rely on multithreading, such as running parallel test suites or building projects with high concurrency, are significantly slower.

For example:

  • A shared runner may take twice as long to run tests compared to a multithreaded runner.
  • Compute-heavy pipelines experience bottlenecks due to the absence of multi-core processing.

3. Scheduling Delays

Shared runners operate on preemptible instances, meaning they can be terminated or paused at any time by GCP. This can cause:

  • Longer queue times for jobs, especially during high-demand periods.
  • Unpredictable start times, making it difficult to plan pipelines effectively.

High-demand situations can also result in job prioritization for other users, further delaying your pipelines.


4. Virtualization Overhead

Shared runners are virtualized, adding a layer of abstraction between the hardware and the container running your job. This introduces:

  • Performance overhead, slowing down job execution.
  • Limited access to hardware resources, as virtualized runners don’t have direct access to the host machine’s full capacity.

This overhead may seem negligible for smaller tasks but becomes a major hurdle for resource-intensive pipelines.


5. GitLab’s Business Model

GitLab’s shared runners follow a billing-per-minute model, meaning there is little financial incentive for GitLab to prioritize shared runner performance. This leads to:

  • Resource contention, as shared runners are designed to serve multiple users simultaneously.
  • Minimal investments in upgrading infrastructure for shared runners.

As a result, shared runners often lack the stability, reliability, and speed required for high-performance CI/CD pipelines.


Additional Challenges

Beyond the limitations above, shared runners may also suffer from:

  • Stability Issues: Unexpected downtime or update problems, as you have no direct control over the runner’s infrastructure.
  • Compatibility Conflicts: Jobs from multiple users sharing the same runner can lead to incompatibilities, further impacting reliability.

The Solution: Dedicated High-Performance Runners

While GitLab shared runners are a good starting point, serious CI/CD needs call for a better alternative. Cloud-Runner offers dedicated runners optimized for speed and efficiency.

Why Choose Cloud-Runner?

  • Dedicated Resources: Each runner is exclusive to your pipelines, eliminating resource contention.
  • Multithreading Support: Fully utilize multi-core processing for faster execution.
  • High-Speed Networking: Drastically reduce pipeline wait times.
  • Predictable Performance: Avoid scheduling delays and ensure reliability.

Real-World Impact

A large enterprise client recently switched to Cloud-Runner and experienced:

  • 50% faster builds thanks to multithreading.
  • Zero queue times, enabling predictable and timely deployments.
  • Improved developer productivity, as teams no longer wasted time waiting for pipelines.

Conclusion

While GitLab shared runners provide a simple and free solution for CI/CD pipelines, their inherent limitations make them unsuitable for resource-intensive workloads or high-demand environments. If your team is dealing with slow pipelines, it’s time to consider upgrading to a dedicated runner solution like Cloud-Runner.

With Cloud-Runner, you can:

  • Slash pipeline times by up to 10x.
  • Enjoy reliable, high-performance infrastructure.
  • Focus on delivering code, not waiting on builds.

👉 Try Cloud-Runner today and transform your CI/CD experience!

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